Pushing the VK45DE to 700Hp with a bigger supercharger!

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My Ex boss Mike, through another new engine in the works. The issue with the remote oil filter housing was sorted out and all the pipes have been cleaned. At some stage, we bought Whipple W200AX supercharger for one of the engine projects at work. When we got the supercharger it was physically just way too big for the engine. The supercharger ended up on a shelf and we almost forgot about it.

I got a phone call from Mike, he asked me whatever happened to the bigger supercharger we bought. When I left the company that was one of the things I put in his office. The charger stood underneath my desk for months. One of the guys at work found it in the graveyard. The graveyard was a section in the building that all the old parts of projects went to. If you needed something for a prototype or for a project you could go in there and look for stuff.

The Supercharger was still wrapped up as the day I left the company. One of my good friends was assigned the job to make the supercharger fit on VK45DE. This was a full custom one-off job. He cut a set of supercharger casing up for this build. He used the intake runners and had to do some mods to them to make the charger fit between them. It wasn’t long and they contacted me to design new drive pulleys for the supercharger and crank.

Getting the build ready

I got a call from Mike, he asked me if I could come through and assist with the mapping of the engine. The aim of this engine was to get 1000 Hp. This was a tall order as the engine still had standard rods and pistons. I told Mike I would try and get as much power out of the engine as I can.

Mike trough a spanner in the works. He wanted to use the new ECU’s that they were getting from a new supplier in Sweden. The company was called NIRA. We have been using there ECU’s for a while and I knew my way around the software.

So let the tuning begin

It took me a good few hours to get the ECU setup before we could crank the engine. The Supercharger was bigger, we had fitted a 4 bar map sensor on the car as well. It has a set of 1000 cc injectors. Everything was different from what we have run before. Eventually, I got the engine started. You could hear that beast of a charger from far away. To give you an idea of the physical size difference here is a comparison.

Left is the 2.3-liter supercharger the Porsche had on and on the right is the 3.3-liter supercharger

To get to a 1000 Hp we would need about 2 bar gauge boost. I didn’t want to stress the system this hard. To start with I did a charger ratio that would give us about 1.3 bar boost. I started to map my way up from Idle. The boost levels was looking really good. At 2500 RPM the engine was making well over 500 Nm of Torque. This engine was insane. At 1500 RPM the engine was making a 0.75 bar boost already. Every 500 RPM the boost was climbing 0.05 bar.

Looking at these figures the engine was going to make good power. We got to 4000 RPM and the belt went on the supercharger. We were running a PK8 Multi groove belt. It looked like the belt was just not up to it. So what now?

How to fix this

I had a look at what the guys with the dragsters run, they all run toothed belts. I designed new pulleys to take an HTD 8M belt, 50mm wide. This is a serious belt on this motor now. If this doesn’t work there are bigger issues. After all the new bits were fitted I was back behind the PC mapping the engine.

I worked my way up the maps and got to 4000 RPM where the belt went last time. The belt worked great but we ran into a wall. The boost climbed all the way to 4000 RPM and the boost stabilized at 1 bar. This was unusual as a supercharger is a positive displacement pump, the faster you spin it the more it pumps. I was baffled, something was wrong. I spoke to Dustin at Whipple superchargers and he said that we had a restriction on the inlet or a big miss-match of the inlet and the supercharger.

What was wrong now

What I found was when the bigger supercharger went on the guys used the old chargers inlet. The inlet was fitted with an adapter plate as the bolt holes were different. This made a step from the smaller inlet manifold to the bigger charger inlet. I phoned Dustin again at Whipple and he said that was my problem. Air does not like to bend. At slower airspeed, it does bend. As soon as the airspeed goes past a certain point it just goes straight.

Air at lower airspeeds. Charger filling up fully.

Blue is good air into the supercharger, red is the unfilled area of rotors.

In the above picture, it does not look like a lot less air but if you view it from the inlet side it is a different story.

Red is the unfilled area of the supercharger rotors at high airspeeds.

I showed this to Mike and he said there is no time to redo the inlet of the supercharger. I must finish the mapping so that the engine can go back into the car. He just wanted to race. I must see what I can get with the setup as is. I told him that they still needed to fit a bypass valve to the supercharger as there was none. He said he doesn’t need one and don’t want one.

Continue mapping the engine

The Maximum boost that I was seeing as 1 bar of boost, all the way from 4000 RPM to 7000 RPM. It was a bit annoying as we know what the issue was but could not fix it. The engine ran really well. We didn’t have any more issues for the rest of the mapping session. We ended up getting 700 HP and 850 Nm of torque with this engine. Mike was extremely happy with this. I knew it could go more but I thought we could fix this at a later stage.

Supercharger VK45DE engine on the engine dyno

I did some acceleration testing on the dyno to make certain the engine is running the best it could. This was a beast of an engine and I just could not wait to see this engine in action.

Engine going back in

It was about 2 days later and I got a call from the guys at the workshop. The Engine is in the car and ready to start. I went through that evening to go set up the engine in the car. The throttles and pedal had to be calibrated. I also had to sort out a gremlin or two.

It was good to see the car back together again. I was still light outside so I took the car out onto the apron for a quick test. This car was insanely powerful, the car actually scared me. It could be because I haven’t driven this car in a good while now. It was fun though to get the adrenaline pumping.

One thing I did notice something. When you start braking coming down from acceleration the car felt like it was still under power for a few seconds. This was due to the fact that there was no recycle valve on the engine. The boost had only one way to go and that was through the engine. This was not an ideal setup but Mike was happy with this.

The Porsche 917 was now once again ready to go race.